Sluggish Cognitive Tempo (SCT): An Explanation of the Syndrome and its Impact on Learning

By Rachel Kallus, Psy. D

How often do you feel tired, spacy, confused, and in your own world as you get through the day? The answer is probably quite different if you are a college student, overnight shift worker, new (or not so new) parent, or a vacationer on the beach. Despite different answers, we have all experienced sluggishness, lethargy, and too much daydreaming at some point. These symptoms are a natural part of the human experience, although at times problematic. The medical, psychiatric, and psychological communities analyze these symptoms to learn more about how the human brain and body functions. A major goal of this research is easily identify and alleviate problematic sluggishness and associated symptoms.

Under the line of research associated with fatigue and sluggishness is interest in a group of symptoms described as sluggish cognitive tempo (SCT). There are many symptoms included under the term SCT, including fatigue, drowsiness, sluggishness, reduced activity levels, and a slowness in thinking, responding, and physically moving.1 Other symptoms of SCT include staring blankly, daydreaming, being in one’s own world, and getting easily confused.1 There is debate as to whether SCT is its own disorder and diagnosis, or if the symptoms reflect traits that co-occur with other disorders and are not an independent condition. Despite uncertainty about SCT as a diagnosis, the literature indicates that the cluster of SCT symptoms are distinct from other conditions, and SCT symptoms can be chronic over time.2,3,4,5 SCT symptoms are typically measured through self-report or informant-report rating scales, and there are no performance-based cognitive or psychological tests that reliably assess SCT.

With the establishment of this group of symptoms that occur together and comprise SCT, research is increasingly focused on the impact of SCT on everyday functioning. Our research group consisting of child psychologists, statisticians, and postdoctoral fellows at Penn State are particularly interested in learning more about the relationship between SCT and school performance. When a student presents with SCT symptoms, one would reasonably assume that these problems affect their ability to think, process information, and learn. Imagine trying to learn long division, how to draw a Punnett square, or recall the capital of South Dakota when you feel tired and sluggish! In order to test such assumptions, our research group conducted a study to determine ways in which SCT symptoms are related to student learning and thinking.

Figure 1. Illustration of student daydreaming, a symptom of SCT. Image source:

In our study, we analyzed relationships between SCT symptoms and academic functioning, academic performance, and cognition in 1,443 students 6 to 16 years old. The sample population was drawn from children in the Pennsylvania region and included children with autism, children with ADHD, children with both autism and ADHD, and a general group of elementary school students. The diagnoses of autism and ADHD were made following a thorough diagnostic evaluation completed by a psychologist. We measured SCT and academic functioning with parent (and some teacher) ratings of children using the Pediatric Behavior Scale (PBS), which assesses many problem areas in children (including SCT, ADHD, misbehavior, and cognitive and learning difficulties). The academic functioning items include difficulty learning even when tries hard; underachieving; trouble with reading, writing, or math; and low grades on school papers and tests. We measured academic performance objectively with achievement tests that assess individual skill levels in the areas of reading, writing, and mathematics. We also measured some aspects of cognition objectively with tests that assess intelligence, working memory (i.e., the ability to briefly hold onto bits of information), and information processing speed.

We calculated multiple types of statistical analyses to examine our data, including Pearson correlation coefficients, analysis of covariance, and regression analysis. Because explanation of statistics can put most people into a sluggish and confused episode, I have summarized some of our most interesting findings:

  • SCT symptoms were significantly correlated with day-to-day academic functioning (e.g., difficulty learning, underachieving, and trouble with academics). However, SCT symptoms did not predict day-to-day academic functioning.
  • For the most part, SCT symptoms were not significantly correlated with scores on achievement tests. There was only one exception. SCT symptoms were significantly correlated with scores on a timed math achievement test, but only in the general group of elementary school students. Meanwhile, SCT symptoms did not predict scores on achievement tests.
  • Regarding cognition, SCT was significantly, but weakly, correlated with processing speed.

We believe our study importantly contributes to the SCT literature by expanding the knowledge of the effects of SCT symptoms on learning. An important take home message is that SCT symptoms were correlated with day-to-day academic functioning. As SCT symptoms worsened, academic functioning also worsened. Even though our analyses indicate this correlation, we cannot say that SCT symptoms cause worsened academic functioning. In fact, SCT symptoms did not predict academic functioning in our analyses. Of note, SCT symptoms were not correlated with scores on achievement tests, and SCT symptoms did not predict these test scores. The next time you feel overly tired, sluggish, and in your own world, know that these symptoms are only partially related to learning. While these symptoms might affect day to day academic functioning, in our study, they were unrelated to test performance!

See our full paper for more on this topic!

Mayes, S.D., Kallus, R., Bangert, L. R., Fosco, W., Calhoun, S. L., & Waschbusch, D. A. (2021). Relationship between sluggish cognitive tempo, IQ and academic achievement test scores, and academic impairment in autism, ADHD, and elementary school samples. Child Neuropsychology.

TLDR: Sluggish cognitive tempo (SCT) describes symptoms of fatigue, sluggishness, daydreaming, and confusion. SCT symptoms are associated with day-to-day learning and functioning in school, but not with academic test scores!


  1. Becker, S. P., Leopold, D. R., Burns, G. L., Jarrett, M. A., Langberg, J. M., Marshall, S. A., et al. (2016). The internal, external, and diagnostic validity of sluggish cognitive tempo: A meta-analysis and critical review. Journal of the American Academy of Child and Adolescent Psychiatry, 55, 163-178.
  2. Dvorsky, M. R., Becker, S. P., Tamm, L., & Willoughby, M. T. (2019). Testing the longitudinal structure and change in sluggish cognitive tempo and inattentive behaviors from early through middle childhood. Assessment, 28, 380-394.
  3. Leopold, D. R., Christopher, M. E., Burns, G. L., Becker, S. P., Olson, R. K., & Willcutt, E. G. (2016). ADHD and sluggish cognitive tempo throughout childhood: Temporal invariance and stability from preschool through ninth grade. Journal of Child Psychology and Psychiatry, 57, 1066-1074.
  4. Mayes, S. D., Calhoun, S. L., & Waschbusch, D. A. (2020a). Sluggish cognitive tempo in autism, ADHD, and neurotypical child samples. Research in Autism Spectrum Disorders, 79, doi: 10.1016/j.rasd.2020.101678.
  5. Mayes, S. D., Calhoun, S. L., & Waschbusch, D. A. (2020b). Relationship between sluggish cognitive tempo and sleep, psychological, somatic, and cognitive problems and impairment in children with autism and children with ADHD. Clinical Child Psychology and Psychiatry, doi: 10.1177/1359104520978459.

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